Two managing directors of Greenhill & Co Inc
Jeffrey Buckalew, 45, head of Greenhill's North American advisory activities, was believed to have been on the plane with his wife and two children.
Also believed to have been on board was Rakesh Chawla, 36, a Greenhill financial services sector banker, the firm said.
New Jersey State police Trooper Christopher Kay said five people were confirmed dead, but could not comment on their identities as the investigation was continuing.
The single-engine Socata plane took off from New Jersey's Teterboro Airport and was headed for DeKalb Peachtree Airport near Atlanta, Federal Aviation Administration spokesman Jim Peters said.
The plane belonged to Buckalew, who joined Greenhill in 1996 from Salomon Brothers. He was an experienced pilot with a passion for flying, Greenhill said, adding it had no further information on the crash.
Before the crash, the plane made contact with an air traffic controller asking for permission to seek higher altitude, which was granted, Peters said. Following this, the transmission became garbled and the plane fell off the radar, he added.
Jeff was one of the first employees of Greenhill. He and Rakesh were extraordinary professionals who were highly respected by colleagues and clients alike, Greenhill Chairman Robert Greenhill and Chief Executive Scott Bok said in a joint statement. They will be sorely missed and our sympathies go out to their families and friends.
Buckalew had served as an adviser for Delta Air Lines during merger talks with Northwest Airlines. He also worked on Roche's squeeze-out of Genentech, and Dow Chemical's Rohm & Haas deal. Other deals included Baker Hughes' sale to BJ Services, Ceridian's sale to Thomas H. Lee Partners and Fidelity National Financial, LNR Property Corporation's sale to Cerberus Capital Management, Roche's hostile acquisition of Ventana Medical Systems, IHOP's acquisition of Applebee's International, Emerson's acquisition of Chloride Group Plc and Emerson's acquisition of Avocent.
Chalwa had joined the firm in 2003 from The Blackstone Group.
(Reporting by Greg Roumeliotis in New York, additional reporting by Jessica Hall in Philadelphia; Editing by John Wallace, Richard Chang, Gary Hill)